The interpretation of INA 245(k) is:

u can still AOS under 245(a) even if
u worked unauthorized,out of status, or in violation of any other terms underlying ur visa status (H1, or B1 or any) as long as the following conditions are met:
1. working w/o authorization, out of status or any violation does not exceed 180 days.
2. at the time you filed ur 485, u are in a legal status & in the US.

In ur example: if u worked w/o EAD or working visa, as long as the days u worked w/o an EAD does not accumulate over 6 months, u can still AOS under 245(a).

203 (b) talks about Preference Allocation of EB catagory immigrants.
101(a)(27) talks about special immigrant.
as a layperson, u shall not worry about all the sections, the key is 245(k) gives u 180 days grace period to file/renew status, get EAD w/o affecting ur chance of getting ur LPR.